A plurality of compression chambers are formed between first and second spiral bodies 1 and 2, and refrigerant discharge timing advancing means is provided for advancing the timing at which refrigerant is discharged from a first compression chamber 4 which is one of a pair of compression chambers located nearest to the center, relative to the refrigerant discharge timing of the second compression chamber 5. The refrigerant discharge timing advancing means includes an extension 1c of the first spiral body 1 and an opening advancing portion 3a of a discharge port 3. <IMAGE>